Mentha arvensis Linn. Var piperescens. Holmes (methol or Japanese mint) is a highly valued industrial crop due to menthol, which is purified by crystallization through freezing from its essential oil. At CIMAP continuous improvement of the genotypes leading to betterment of different commercially important characters are underway. One of-the critical steps in menthol mint cultivation is the date of planting which determines the optimum yield of menthol after harvesting. In India the planting duration extends from mid of January to first quarter of February. Prior to planting the crop during this period, a small portion of land is used for sucker production during the month of September to January. During this period the underground suckers multiply vigorously which are used for planting in the main field.
But the sucker planting of mint during January and February (the normal planting time) interferes into the Rabi season crops like wheat, chickpea, coriander etc having a full grown crop stand at that time to be harvested at the mid to end of April. The Rabi cropping season starts at September-October to April-May. Planting in the month of January-February thus leads to the compromise for some of the Rabi harvest. The existing varieties of mints if planted late, i.e. in March-April show significant reduction in the biomass yield. In the varietal improvement programmes, the genetic alternations leading to enhancement in the menthol content in the essential oil and improving other adaptive characters determining the yield and quality of essential oil are most desirable.
So we planned experiments for developing a genotype which can be transplanted through stem cuttings instead of sucker planting after the Rabi harvest in mid April and also through sucker mode during normal planting in January-February without compromising on yield. The most desirable trait for such a genotype would be high and rapid regenerability of cuttings and that is what was achieved in the plant ‘Kushal’ of Mentha arvensis. 